Earth-Type Planets

About 400 “extrasolar” planets orbiting nearby stars have been detected since 1995, starting with a discovery made by the same team, led by Switzerland’s Michel Mayor, of a Jupiter-sized planet orbiting the star 51 Pegasi, 50 light-years away. (One light-year is about 5.9 trillion miles.), reports.

“We are on the good track to detect (indirectly) Earth-type planets within the next five to 10 years,” Udry says. Using the European Southern Observatory’s 11.8-foot-wide telescope at Chile’s La Silla Observatory, the team detects planets by “radial velocity” measure, which reveals the gravitation wobbles induced on stars by their planets.

“Wow — 32 or so planets at once — that certainly is a record for the largest number of new planets announced at the same time,” says planetary scientist Alan Boss of the Carnegie Institute of Washington. “It really shows that the Europeans have taken the lead” in radial velocity planet hunting, he adds.

The team announced the newly discovered planets at a science meeting in Porto, Portugal. They range in size from 5.4 times more massive than Earth to 7.1 times heavier than Jupiter, the largest planet in our solar system, and their host stars ranged from about 30 to 150 light-years away. Two of the “Super-Earths” — thought to be rocky planets like Earth and not gas giants — orbit stars like our sun, and the other two orbit smaller “M” class stars, dimmer and redder than the sun.

So “we have yet to find firm evidence for a habitable, Earth-mass planet,” Boss says. But he says the Super-Earth detections suggest that upcoming planet hunts, including NASA’s Kepler spacecraft, should find “lots of Earths.”

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